Electric drive of air-screw propelled cars



Dec. 21, 1937. H. FRASER 2,103,156

ELECTRIC DR-IVE OF AIR SCREW PROPELLED CARS Filed Sept. 27, 1934 2 Sheets-Sheet 1 4 I757? a 9 F ,16 5 25 2 1F" 10 H12 3 i j 5 FL W I a 1 pvvezx/TOB Dec. 21, 1937. FRAISER 2,103,156

ELECTRIC DRIVE OF AIR SCREW PROPELLED CARS Filed Sept 27, 1934 2 Sheets-She et 2 Patented Dec. 21, 1937 ELECTRIC DRIVE 0F: AIR-SCREW mo:

I PELLEDQCARS.

Hugh Fraser, Burnside,

Rutherglen, Scotland; as-

signor to Inter CountieslLimitel; Glasgow,

Scotland Application September 27, 1934, Serial No. 745,824 In Great Britain February 28,1934

1 Claim.

This invention has reference to electric drives of air-screwpropelled cars, aircraft, and the like, suspended from overhead tracks. 7

My invention has for its object to provide an '5 improved power unit for such cars and the like.

Another object of the invention is to provide an improved power unit in which torsional vibrations are more effectively damped than has heretofore been found possible.

Preferred embodiment of the invention will now be described byway of example with reference to the annexed drawings.

On the annexed two sheets of drawings:-

Figure 1 is a sectional elevation of a driving unit, the unit being shown fitted to a car, in accordance with the invention and with single motor.

Figure 2 is a section on the line A-A, Figure 1.

Figure 3 is an elevation partly in section of a pair of pinion wheels with clutch device incorporated therein. 7

Referring to the drawings:-

l is an electric motor of standard design but provided with a hollow armature shaft 2, journailed in ball bearings 3 and 4 carried by two end covers 5 and 6 of the motor casing 1.

Extending through the armature shaft 2 is the air-screw shaft 8 to which is keyed the air-screw 8 Said shaft at its inner end, that is the end 80 remote from the air-screw, is journalled in a double thrust bearing 9 carried by the inner end cover 5 of the motor casing. Fast on the outer end of the armature shaft is a spur wheel It with which mesh a number of pinion wheels H of special construction, the shaft of each of which has formed integral therewith a smaller pinion wheel II. The latter in turn mesh with a spur wheel l2 fast on the air-screw shaft 8. The shafts of each pair of pinion wheels II and H are, at their inner ends, journalled in ball bearings l3 housed in annular recesses formed in the outer face of the outer endcover 6 of the motor casing. The other ends of said shafts are journalled in ball bearings I4 housed within annular recesses formed in a plate l5 which constitutes a gear cover. Said plate is provided with a hub l6, within which is accommodated a ball race I! through which the air-screw shaft extends. The commutator is located at the end of the motor remote from the air-screw.

The outer cover plate 6 of the motor casing is provided with a spider l8 having a flange I9 which conforms to and is adapted to be attached to the body 20 of the car or air-craft and to this flange is secured skin plating 2| which is formed in sections, is of truncated conical formationand extends to and is attached to the said gear cover plate I5.

Attached to the air-screw shaftis a light sheet metalcasing, which is intended to revolve with the air-screw, and to conform to the shape of the car. It consists of a circular diaphragm plate 22 fixed to a flange 23 attached to the air-screw shaft and attached to a machined fla'nge24at its outer diameter, together with a portion of skin plating extending between'the blades of "the airscrew and a portion ofskin-plating 25-which- 'is located and fixed with the locking arrangement of the air-screw nut 26. With wooden air-screws this shaped-revolving-nose of the car would be made in whole or in part asan integral part of the air-screw boss.

The pinions ll of special construction above referred to are formed by a series of plates 21 mounted so as to rotate with their shafts, said plates taking every alternate plate in a multiple plate clutch, see Figure 3. Every other plate 28 is taken by the pinion wheel which is located axially and circumferentially by the covers 29 of the plate clutch. For this purpose a recess is formed in the inner cover and a ring 30 split across a diameter is inserted in this recess and bears against the ends of the splines formed on the shaft so that the pinion wheel is located axially. The whole is held together with bolts or studs with spring washers and pressure between the plates of the clutch is thus adjusted and maintained. These pinion wheels engage with the gear wheel fixed to the armature shaft as aforesaid.

It will be noted that the motor, casing, airscrew shaft and air-screw can be assembled into one unitfor attachment to the car. The skinplating 2| covering the gearing on being removed allows of a temporary bracket being attached to the outer motor casing cover so that the unit can be suspended above its centre of gravity for removal from the car. The advantages of. this are as follows:- 7

(a) Complete driving units can readily be taken out and be replaced for any cause whatsoever.

(b) The air-screw can be matched with the remainder of the unit as regards balance before attachment to the car. 7

With a motor directly coupled to an air-screw a compromise has to be made between the best motor speed and best air-screw speed. And since there is very little variation in air-screw rotational speed as the car speed increases from rest be designed for their best speeds if a reduction gearing such as is shown is incorporated, the gear ratio being equal to the ratio of best airscrew speed to best motor speed.

Again, as the lineal speed of the air-screw blade at its extremity is a function of the extent of propeller noise, a practically silent air-screw can be arranged for without undue sacrificein over-all efliciency.

Further, the arrangement set forth also permits of streamlining that portionqof the air-screw, namely, the boss and roots of the blades,,-,which; add to the inefiiciency of. the air-screw if exposed in moving air.

powere The vintentiom.therefore; is to simplify assembly and by suitably {adjusting ;the pressure 'betweenplatesto ensure that each shaft takesan 7 almost equal amount of power, and if torsional variations are set up in the air-screw shaft due to sidetwinds on the air-screw blades, the-plate clutches Joy slipping will damp-these oscillations "and prevent excessive' torsional stresses in the airscrew and armatureshaft.

What I claim is:- 7

An electric drive for air-screw propelled cars and the like, comprising an electric motor having a hollow armature shaft, a casing having end covers for said motor, bearings carried by said end covers in which the hollow armature shaft is journalled, an air-screw sha-ft extending completely through the armature shaft-further bearnalled, said airescrew shaft extending beyond one oi -the end covers, an air-screw fast on the extended end of the air-screw shaft, a pinion wheel fast onthe armature shaft, a set of pinion wheels The arrangement of plate clutch inconnection meshing with and arranged symmetrically around said pinion wheel, a further set of pinion wheels co axia-lewith" andadriven by the first set, each pinion wheel-of one of the sets embodying fast meshso' as to drive the air-screw shaft without imparting anytransverse ,thrustthereto, the fast and;.slippin g.,pl ates. ensuring that each of the intermediate;pinionsvtransmitsits fullshare of V the drive, absorbing shock and eliminating torsionalivibration p d g; r I

, 1 HUG;I I-=FR.ASER.' 

